In cellular mobile radio communication networks (e.g. UMTS (Universal Mobile Telecommunications System), LTE (Long Term Evolution)) coverage is based on overlapping cells. Each mobile radio cell may include at least one base station (in UMTS called NodeB and in LTE called eNodeB). The behavior of a mobile radio communication device that is moving through different mobile radio cells is dependent on the state the mobile radio communication device is in. In a so-called “active” state (e.g. user is in a call) the mobile radio communication network usually triggers a handover from one mobile radio cell to another based on measurements performed by the mobile radio communication device. In a so-called “idle” state (e.g. user is only ready to be called) the mobile radio cells are divided into groups. Such a group is called a “Location Area”, “Paging Area” or “Tracking Area”. If the mobile radio communication network tries to establish a mobile radio communication connection with the mobile radio communication device, the mobile radio communication device is usually paged in the whole paging area. If the mobile radio communication device receives the paging, it switches into active state and registers in the current mobile radio cell. Within one paging area a mobile device in idle state does not register and de-register to single mobile radio cells. Therefore, the mobile radio communication network is not aware of the current mobile radio cell the mobile radio communication device is in. If the mobile device in idle state leaves a paging area and enters another one the mobile radio communication device makes a Location Area Update (LAU) via a random access channel which is a shared resource.
In a cellular mobile radio communication network according to LTE standards, the access network is conventionally not only built of standard mobile radio base stations but also of so-called Home (e)NodeBs (HNB). As a mobile radio cell with a mobile radio base station is also called mobile radio macro cell a mobile radio cell with an HNB may also be called mobile radio femto cell. An HNB is a consumer device that is connected to the mobile radio core network via fixed line (e.g. DSL) or wireless to a mobile radio macro cell. It provides access to legacy mobile devices and increases the coverage in buildings and the bandwidth per user. An HNB could be run in open or closed mode. In closed mode the HNB provides access to a so-called closed subscriber group (CSG) only. Examples for such closed subscriber groups are families or some or all employees of a company, for example.
Conventionally, the HNB has no information about mobile radio communication devices entering the mobile radio cell in idle state. As long as the mobile radio cell belongs to another paging area as the mobile radio macro cell at least some elements in the mobile radio communication network were informed whether a mobile radio communication device is within an HNB, but there does not exist any means to pass on this piece of information to the HNB. A(n) (e)NodeB conventionally is stateless, which means it has no information of the identity of the users in the mobile radio cell.